discord.js error

TypeError: Cannot read properties of undefined (reading 'create')
at createTicket (C:\Users\Admin\Desktop\Coding\Opnium\OpniumTicketSystem\index.js:99:43)
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
at async Client.<anonymous> (C:\Users\Admin\Desktop\Coding\Opnium\OpniumTicketSystem\index.js:63:24)

async function createTicket(forumChannel, user, ticketType, interaction) {
    console.log('Creating ticket in forum channel:', forumChannel);

    if (!forumChannel || forumChannel.type !== ChannelType.GuildForum) {
        throw new Error("Invalid forum channel.");
    }

    
    const threadsManager = forumChannel.threads;
    if (!threadsManager) {
        throw new Error("Threads manager is undefined.");
    }

    console.log(`Threads manager available: ${threadsManager}`);

    
    try {
        const thread = await threadsManager.create({
            name: `[OPEN] - ${user.username} - ${ticketType}`,
            autoArchiveDuration: 1440, 
            reason: `New ${ticketType} ticket from ${user.username}`,
            message: {
                content: `Hello ${user}, this is your ${ticketType.toLowerCase()} ticket. Our team will assist you shortly.`,
            },
        });

        
        await thread.permissionOverwrites.create(user.id, {
            ViewChannel: true,
            SendMessages: true,
            ReadMessageHistory: true,
        });

        return thread;
    } catch (error) {
        console.error('Error creating thread:', error);
        throw error; 
    }
}